Afaan Oromoo is spoken across a wide area of east Africa. There are maybe common features that have been identified but an official dialect has not been created or confirmed for things written in the language. These differences can be like preference for certain words or sentence structures but the other option is allowed or at least clearly understood. I would think of the multiple ways to say the word egg that exist, or the fact that western Oromoo dialects often use rhe copula verb dha (the unchanging conjugation of the ver ta’uu) in many more sentence situation than it is used in eastern Oromoo dialects. I initially lived somewhere where my exposure was almost entirely to the western dialects but now I hear eastern dialects the most often.
There are probably many that I encounter and pass off as equally valid and barely notice at this point but Lukkuu Cimtuu has one that is difficult to miss. This is the difference between saying akkam and saying attam in a question like akkam bulte/attam bulte. Both of these spellings and pronunciations exist, but I more commonly encountered akkam bulte where I lived. It was still always fun to walk down the road and meet one of the handful of people who had grown up in a different region and greeted me with an attam bulte in the morning.
There are even larger differences between the language where I lived and places like Borana or further into Kenya with the Waata dialect. When I am reading things that were written with these dialect pronunciation spellings it is always difficult at first even if there are also many commonalities. I haven’t had much chance to speak with someone from these areas but when I have been able to hear it in passing it is more difficult for me.